In order to become a skilled rider, a horseback rider usually develops a good sense of balance while seated. The rider must become adept at remaining balanced atop a horse as the horse moves beneath the rider.
Good seated balance benefits both the rider and the horse. When the rider is well balanced, she is better able to stay in control on the horse, and the horse is better able to move beneath the rider. This is particularly important where the horse is performing demanding tasks such as jumping, quickly accelerating or decelerating, running at high speed, or changing direction suddenly.
Kayaking is also an activity that requires seated balance, as a kayaker must remain balanced with her center of mass typically positioned above a kayak as the boat pitches, rolls, yaws, changes direction, and accelerates/decelerates beneath her.
Most devices for developing balance are adapted for use while the user is supported by his or her limbs. For instance, devices and exercises where a user stands on an unstable surface, often on only one foot, are well known. Such devices do little for seated balance.
Exercise balls are devices adapted to seated balance training A user can sit on the exercise ball and lift her feet from the ground, thereby requiring the user to balance on the ball in a seated position. However, it is difficult to limit range of motion on an exercise ball, and the balls typically have three translational, as well as rotational, degrees of freedom; they usually roll across a support surface when the user loses her balance. The property of rolling makes the exercise ball ill suited for a seated balance training device for horseback riding.
Moreover, an exercise ball is typically 45 cm or greater in diameter, which places the user relatively high above a point about which the user rotates as the ball rolls. Conversely, a kayak typically rotates about a point just beneath a kayaker as the kayak pitches, rolls, and yaws in water. Accordingly, balancing on exercise balls is relatively poor seated balance training for kayaking.